/Engine/Plugins/Editor/UVEditor/Source/UVEditor/Public/UVEditorModeUILayer.h
Called by SLevelEditor to notify the toolbox about a new toolkit being hosted
virtual void OnToolkitHostingStarted ( const [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [IToolkit](API\Editor\EditorFramework\Toolkits\IToolkit) > & Toolkit )